Preamp with tone control - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Pass Labs This forum is dedicated to Pass Labs discussion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 7th February 2006, 09:37 AM   #1
hates ground loops
diyAudio Member
Rodeodave's Avatar
Join Date: Dec 2004
Location: in the alps
Blog Entries: 1
Default Preamp with tone control


Maybe this is not considered high-end, but neither my speaker(s) nor my room has a flat frequency-response.
And sometimes some tracks need more base/mid/treble, whatever.

Well...I've tried to "design" an unbalanced preamp with built-in tone control. (-> differential pair, tone control, mixing stage)

I didn't want to use inductors, so I've tried to gyrate capacitors (=transforming capacitance into inductance, inversely proportional) using FETs.
It's possible to gyrate a capacitor using tubes or op-amps. To keep up the spirit, I want to use FETs, but I don't want to diy op-amps directly (too many parts).

Simulating it with circuitmaker indicated that some of my part's values are wrong. There's no effect on the signal, I think because the FETs in the gyrating stage are not turned on. And there's no gain.

The idea is to use the balanced zen pre as a differential pair, tone control with gyrated caps instead of inductors and a simple mixing stage (mixing the pure signal with the tweaked signal).

Maybe someone can help me fix the circuit.

Yarr, Dave
Attached Images
File Type: jpg zen_eq.jpg (58.6 KB, 859 views)
Gravity - Making the G since 13.7 billion B.C.
  Reply With Quote
Old 7th February 2006, 07:04 PM   #2
The one and only
Nelson Pass's Avatar
Join Date: Mar 2001
Here's an old one I used from 1974 which may help you.
Attached Images
File Type: gif gyrator.gif (30.1 KB, 788 views)
  Reply With Quote
Old 7th February 2006, 08:48 PM   #3
diyAudio Member
hifimaker's Avatar
Join Date: Oct 2003
Location: San Jose
Tone controls?? That's Sacrilege!

Egads... more stuff in the signal path.

  Reply With Quote
Old 7th February 2006, 11:05 PM   #4
wchick is offline wchick  United States
diyAudio Member
Join Date: Jul 2002
Location: Colorado
I think if you cannot make the sound in good tonal balance, you will never listen to "music".

  Reply With Quote
Old 8th February 2006, 03:50 PM   #5
hates ground loops
diyAudio Member
Rodeodave's Avatar
Join Date: Dec 2004
Location: in the alps
Blog Entries: 1
Yep, it's Sacrilege. And there are more parts to the signal path, I agree.

But sometimes I just can't cope with how some tracks are mixed. Some old Beastie Boys records need more base (esp. License to ill), some recordings of Dvorak (Nr.9) are, for my taste and on my system, a bit flat in the mids, Aphex Twin loves the highs,...

I want simple tone controls, embedded in a pre-amp. That is it.

Mr. Pass,

I can't figure out the value of the middle cap, is that 3F? And the bypass cap (at the transitor), is that 10F?! And what kind of transistor should I use, maybe a TIP... or MPSA..., or can i use an n-chanel FET?

Thanks a lot, Dave
Gravity - Making the G since 13.7 billion B.C.
  Reply With Quote
Old 12th June 2011, 07:22 PM   #6
diyAudio Member
Bob Richards's Avatar
Join Date: Feb 2011
Location: Portland Oregon, USA
Anyone who buys in to that malarky that tone controls are bad, is a sucker.
  Reply With Quote


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
My active preamp/tone-control and TL074 kaushama Chip Amps 27 13th June 2011 01:54 PM
Tube preamp, tone control problem Ahmad_tbp Tubes / Valves 17 9th March 2011 11:56 PM
i need preamp schematics w/o tone control or volume control hernanstafe Parts 7 30th January 2008 03:12 AM
TI's Tone control JhonDoe Chip Amps 26 13th July 2004 01:29 AM

New To Site? Need Help?

All times are GMT. The time now is 03:55 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2